Pneumatic control system and reset valve for such a system or the like

ABSTRACT

A pneumatic control system having a source of control fluid providing two different control pressure levels for respectively switching the control device of the system from one operating condition thereof to another operating condition thereof, the control device comprising a pair of condition controller means each having a sensor and a bleed-type pneumatic valve operated thereby together with relay means operatively interconnected to the source for directing a branch signal of the control fluid to the source for directing a branch signal of the control fluid to a pneumatically operated device in relation to a pilot signal directed to a pilot chamber of the relay means by one of the control means. A pressure responsive means is provided for switching the system from one condition controller means to the other in relation to the pressure level of the source, and a reset means is provided for overriding the pressure responsive means.

United States Patent [72] Inventor Louis M. Poster Knoxville, Tenn. 21Appl. No. 16,479 [22] Filed Mar. 4, 1970 [45] Patented Aug.31,1971 [73]Assignee Robertshaw Controls Company Richmond, Va.

[54] PNEUMATIC CONTROL SYSTEM AND RESET VALVE FOR SUCH A SYSTEM OR THELIKE 14 Claims, 9 Drawing Figs.

[52] U.S. Cl 137/84, 236/47,236/82, l37/ll3,l37/85, 137/118 [51 1 Int.Cl .G05d 23/00, G05b 11/50 [50} Field ofSearch 137/84, 85, 86, 113, 118;236/47 [56] References Cited UNITED STATES PATENTS 3,312,710 10/ 1965Nilles 23 6/47 3,305,172 2/1967 Duchek Primary ExaminerAlan CohanAttorneys-Auzville Jackson, .lr., Robert L. Marben and Candor. Candor &Tassone ABSTRACT: A pneumatic control system having a source of controlfluid providing two different control pressure levels for respectivelyswitching the control deviceiof the system from one operating conditionthereof to another operating condition thereof, the control devicecomprising a pair of condition controller means each having a sensor anda bleed-type pneumatic valve operated thereby together with relay meansoperatively interconnected to the source for directing a branch signalof the control fluid to the source for directing a branch signal of thecontrol fluid to a pneumatically operated device in relation to a pilotsignal directed to a pilot chamber of the relay means by one of thecontrol means. A pressure responsive means is provided for switching thesystem from 1 one condition controller means to the other in relation tothe pressure level of the source, and a reset means is provided foroverriding the pressure responsive means.

PATH-HEB AUG31 l9?! SHEET 2 BF 3 FIG.3

. INVENTOR. LOUIS M. PUSTER PNEUMATIC CONTROL SYSTEM AND RESET VALVE FORSUCH A SYSTEM OR THE LIKE system as well as to a reset means for such apneumatic control system or the like.

It is well known from the aforementioned patent application thatpneumatic control systems have been provided wherein a pneumatic sourcehas two different control pressure levels so that the system willoperate a pneumatically operated device in one manner when the source isproviding one of the control pressure levels and will operate thecontrol device in another manner when the pneumatic sources is providingthe other control pressure level thereof.

For example, such control systems have been provided for controllingpneumatically operated heat exchanger devices of a building or the likewherein the one control pressure level is utilized to operate thepneumatically operated heat exchanger device for daytime operationthereof and, at nighttime, the control pressure of the pneumatic sourceis changed over to provide its other control pressure level foroperating the heat exchanger device for nighttime operation thereof.

One of the features of the aforementioned patent application is toprovide a pneumatic control system of the above described type whereintwo condition controller means are provided for the system torespectively operate at the different control pressure levels and eachhaving a sensor and a bleedtype pneumatic valve operated thereby.

In contrast, one of the features of this invention is to provideimproved reset means for such a control system or the like wherein suchreset means can be manually operated to reset the system to dayoperation when it is operating at night operation.

In particular, one embodiment of this invention provides a pneumaticcontrol system comprising a pair of condition controller means eachhaving a sensor and a bleed-type pneumatic valve operated thereby forrespectively directing a pneumatic pilot signal to a pilot chamber of arelay means which is operatively interconnected to the pneumatic sourcefor directing a branch signal of the control fluid to the pneumaticallyoperated device in relation to the particular pilot signal beingreceived in the pilot chamber thereof. First and second passage meansare respectively provided to be adapted to interconnect the source tothe valves of the controller means, a pressure responsive means beingdisposed in the first passage means for preventing fluid communicationtherethrough when the source is at one pressure level thereof andpermitting fluid communication therethrough when the source is at itsother pressure level. A third passage means is adapted to interconnectthe first passage means intermediate the pressure responsive means andthe one controller means to the pilot chamber and is adapted tointerconnect the second passage means to the pilot chamber, a switchingmeans being disposed in the third passage means and having one positionfor interconnecting only the second passage means to the pilot chamberwhereby the pilot signal for the relay means is provided only by theother controller means and having another operating position forinterconnecting only the first passage means to the pilot chamberwhereby the pilot signal for the relay means is provided only by the onecontroller means. The reset means is disposed in fluid communicationwith the first passage means between the pressure responsive means andthe one controller means, the reset means venting the switching means tothe atmosphere so that the other controller means is operative when thereset means is manually operated to a reset position thereof and thepressure responsive means is attempting to cause operation of the onecontroller means.

Therefore, it is an object of this invention to provide an improvedpneumatic control system having one or more of the novel features setforth above or hereinafter shown or described.

Another object of this invention is to provide an improved reset meansfor such a control system or the like, the reset means having one ormore of the novel features set forth above or hereinafter shown ordescribed. I

Other objects, use and advantages of this invention are apparent from areading of this description which proceeds with reference to theaccompanying drawings forming a part thereof and wherein:

FIG. 1 is a front view of the improved control device of this inventionwith the cover plate thereof removed.

FIG. 2 is a schematic view, partially in cross section, illustrating theimproved pneumatic control system of this invention utilizing thecontrol device of FIG. 1.

FIG. 3 is an enlarged, exploded perspective view of certain of the partsof the control device of FIG. 1.

FIG. 4 is a fragmentary, enlarged side view of the control device ofFIG. 1 and illustrates the adjustment means for the condition controllermeans of the control device.

FIG. 5 is a view similar to FIG. 4 and illustrates the conditioncontroller means in another adjusted position thereof.

FIG. 6 is an exploded perspective view of the reset means of the systemof FIG. 2.

FIG. 7 is a fragmentary cross-sectional view of the reset means in itsnormally open position.

FIG. 8 is a view similar to FIG. 7 illustrating the reset means in itactuated and closed position.

FIG. 9 is a cross-sectional view taken on line 9-9 of FIG. 8 andillustrates in phantom lines the reset position of the reset means.

While the various features of this invention are hereinafter describedand illustrated as being particularly adapted to provide a pneumaticcontrol system for controlling a pneumatically operated heat exchangingdevice, it is to be understood that the various features of thisinvention can be utilized singly or in any combination thereof toprovide control means for other apparatus as desired.

Therefore, this invention is not to be limited to only the embodimentsillustrated in the drawings, because the drawings are merely utilized toillustrate one of the wide variety of uses of this invention.

Referring now to FIG. 1, the improved control device of this inventionis generally indicated by the'reference numeral 10 and comprises ahousing means 11, illustrated in fragmentary cross-sectional portionsin. FIG. 2 wherein the improved control system of this invention isgenerally indicated by the reference numeral 12 and comprises apneumatic control source 13 adapted to selectively supply pneumaticpressure fluid at two different pressure levels, such as 16 p.s.i. and25 p.s.i. and be interconnected to an inlet passage means 14 of thecontrol device 10. The control device 10 is adapted to have an outletpassage 15 thereof interconnected to a pneumatically operated device 16of the system 12. The pneumatically operated device 16 of the system 12of this invention comprises a pneumatically operated heat exchangingdevice which has its output temperature effect decreased upon anincrease in pneumatic pressure fluid being directed thereto by thecontrol device 10 of this invention in a manner hereinafter describedand has its output temperature effect increased upon a decrease in thepneumatic pressure fluid being directed thereto by the control device 10of this invention in a manner hereinafter described.

The housing 11 of the control device 10 as illustrated in FIG. 2 carriesa pair of condition control means respectively and generally indicatedby the reference numerals I7 and 18 in FIG. 2 and comprising bleed-typepneumatic valves 19 and 20 respectively having the degree of opening orbleed of their outlets 21 and 22 controlled by bimetal members 23 and 24respectively sensing the output temperature effect of the heat exchangermeans 16 and respectively being carried in cantilevered fashion bylevers or blade means 25 and 26, FIGS. 1 and 3, mounted to the housingmeans 11 of the control device 10.

In particular, the lever or blade means and 26 respectively had adjacentends 27 and 28 interconnected to leaf springs 29 and 30 at the ends 31and 32 thereof with the leaf springs 29 and 30 respectively having theother ends 33 and 34 thereof fixed to the housing means 1 1 of thecontrol device 10 by fastening means 35 and 36 as illustrated in FIGS. 1and 4 so that the free ends 37 and 38 of the blades 25 and 26 arenormally urged downwardly by the leaf springs 31 and 32 in FIG. 4whereby adjusting screws or threaded members 39 and 40 respectivelycarried by the free ends 37 and 38 of the blades 25 and 26 will bearagainst a movable wobble or pivot plate 41 ofthe control device 10.

The pivot or wobble plate 41 carries a pair of downwardly extending pins42 and 43 disposed along a line 44 of the plate 41 that is parallel to aline 45 on the plate 41 that passes through the respective points 46 and47 of engagement of the threaded adjusting members 39 and 40 of theblades 25 and 26 as illustrated in FIG. 3. The housing means 11 of thecontrol device 10 has a cone-shaped hole 48 and a V-shaped notch 49formed therein which respectively receive the pins 43 and 42 of thepivot or wobble plate 41 so that the pivot plate is positively locatedon the housing 11 of the control device 10 and will not rotate thereonabout either pin 42 or 43, a tension spring 50 having one end 51attached to the plate 41 and the other end 52 thereof attached to thehousing means 11 pulls the plate 41 downwardly at all times toward thehousing 11 whereby a forward rounded pin 53 of the pivot plate 41 bearsagainst a cam surface 54 of a cam member 55 rotatably mounted to thehousing means 11 and having a control shaft 56 adapted to beinterconnected to a control knob (not shown) wherein the operator canadjust the cam 55 relative to the control device 10 in relation to atemperature scale 55A, FIG. 1, to set the temperature that controlsystem 12 is to maintain in the manner hereinafter described.

The tension spring 50 of the pivot plate 41 is so located relative tothe three pivots 42, 43 and 53 of the plate 41 that the same is disposedwithin the triangle defined by the three pivots 42, 43 and 53 topositively maintain the plate pivot 53 against the cam surface 54 of thecam 55 in all of the operating positions of the cam 55, the hole 48 forthe pivot pin 43 defining a center of rotation for the plate 41 and theV-shaped notch 49 for the pivot pin 42 preventing such rotation wherebythe pivot plate assembly 41 is positively located on the housing means11 of the control device 10. In this manner, rotation of the cam 55 willcause the plate 41 to pivot about the pivot line 44 in the mannerillustrated in FIGS. 4 and 5 to adjust the location of the free ends 37and 38 of the levers or blades 25 and 26 relative to the housing means11 and, thus, the position of the bimetal members 23 and 24 relative tothe bleed valves 19 and 20 whereby the control setting of the conditioncontroller means 17 and 18 can be adjusted for a purpose hereinafterdescribed.

The levers or blades 25 and 26 respectively have rectangular openings 57and 58 passing therethrough intermediate the opposed ends thereof andthe bimetal members 23 and 24 respectively have the ends 59 and 60thereof secured to the blades 25 and 26 in such a manner that the freeends 61 and 62 of the bimetal members 23 and 24 are exposed at thecutouts 57 and 58 and are located over the valves 19 and 20 of thehousing means 11 as illustrated in FIGS. 4 and 5. In this manner, thesetting of the free ends 61 and 62 of the bimetal members 23 and 24relative to the valves 19 and 20 of the condition controller means 17and 18 can be adjusted by the cam 55 whereby movement of the cam 55adjusts the free ends 61 and 62 of the bimetal members 23 and 24relative to the respective valves 19 and 20 in the same direction towardor away from the valves 19 and 20.-

In the control system 12 illustrated in FIG. 2, both bimetal blades 23and 24 move or warp toward their respective valves 19 and 20 upon anincrease in sensed temperature and move or warp away from theirrespective valves 19 and 20 upon a decrease in sensed temperature.

In this manner, the bimetal member 24 controls the heating operation ofthe pneumatically operated heat exchanging device 16 during daytimeoperation and the bimetal member 23 controls the heating operation ofthe pneumatically operated heat exchanging device 16 during nighttimeoperation thereof.

As illustrated in FIG. 2, the housing means 1 l of the control device 10is provided with a first passage means 66 that is adapted to be directlyinterconnected to the source 13 at the inlet 14 of the housing means 11and to the outlet opening 21 of the valve 19. However, a pressureresponsive means 67 is provided in the housing means 11 of the controldevice 10 in the first passage means 66 and is defined by an inlet 68and an outlet 69 separated by a valve seat 70 of the housing 11 with theinlet 68 being interconnected to the part 71 of the first passage means66 that leads from the source 13 and with the outlet 69 beinginterconnected to the part 72 of the passage means 66 that leads to theopening 21 of the valve 19.

The pressure responsive means 67 includes a flexible diaphragm 73 heldbetween housing parts 74 and 75 to cooperate therewith and define achamber 76 adjacent one side 77 of the diaphragm 73 and interconnectedto the inlet 68 and adapted to be interconnected to the outlet 69 whenthe valve seat 70 is opened. The other side 78 of the flexible diaphragm73 cooperates with the housing means 11 to define another chamber 79that is interconnected to the atmosphere through an opening 80 in afitting 81 carried in a threaded opening 82 formed in the housing means11. A member 83 is disposed in the chamber 79 and has one end'84 adaptedto engage against the side 78 of the diaphragm 73 and an opposed guideplunger end 85 that projects out through the opening 80 in the fitting81. A compression spring 86 is disposed in the chamber 79 and has oneend 87 bearing against the fitting 81 and the other end 88 thereofbearing against the enlarged end 84 of the member 83 so as to tend tomaintain the end 84 against the side 78 of the diaphragm 73 whereby themember 83 will follow movement of the diaphragm member 73.

The force of the compression spring 86 is such that the same willmaintain the flexible diaphragm 73 against the valve seat 70 so as toprevent fluid communication through the first passage means 66 when thepressure source 13 is providing a control pressure at the lower of itstwo levels, such as 16 psi. so that when the pressure source 13 is atits lowest control level, the pressure source 13 is not interconnectedto the outlet 21 of the valve 19 of the condition controller means 17since the spring 86 maintains the diaphragm 73 closed against the valveseat 70. However, when the pressure source 13 is set to provide thehigher of its two control pressure levels, such as 25 p.s.i., the forceof the higher pressure level in the chamber 76 of the pressureresponsive means 67 exceeds the force of the compression spring 86 so asto move the diaphragm 73 upwardly and thereby open the valve seat 70 sothat the pressure source 13 at its higher pressure level is fluidlyinterconnected to the outlet 21 of the valve 19 of the conditioncontroller means 17. In this manner, it can be seen that the pressureresponsive means 67 permits fluid communication through the firstpassage means 66 when the pressure source 13 is providing its higherpressure control level and prevents fluid communication through thepassage means 68 when the pressure source 13 is providing its lowercontrol pressure level.

The housing means 11 has a second passage means 89 provided thereinwhich is adapted to interconnect the outlet 22 of the valve means 20 ofthe condition controller means 18 to the source 13, the second passagemeans being illustrated in FIG. 2 as having a branch passage means 90fluidly interconnected to the first passage 66 intermediate the source13 and the pressure responsive means 67. A normally open pressureresponsive valve means 91 is disposed in the passage means 89intermediate the valve 20 of the condition controller means 18 and thesource 13, the normally open pressure operated valve means 91 having apneumatic actuator 92 therefor interconnected by a passage means 93 tothe conduit 72 intermediate the outlet 69 of the pressure responsivemeans 67 and the nozzle 19 so that when the pressure responsive means 67is moved to its open position by the pneumatic source 13 providing thehigher control pressure level thereof, such source 13 is alsointerconnected to the actuator 92 of the normally open pressure operatedvalve means 91 to close the same and thereby prevent fluid communicationthrough the second passage means 89 to the valve 20 of the conditioncontroller means 18.

A restrictor 94 is disposed in the second passage means 89 intermediatethe pressure operated valve means 91 and the source 13.

The housing means 11 of the control device is provided with apneumatically operated switching means 95 therein which, as illustratedin FIG. 2, comprises a pair of inlets 96 and 97 respectively formed inthe housing means 1 1 and being separated from each other by a pair ofsecond valve seats 98 and 99 formed in the housing means 11 and adaptedto be opened and closed by a movable valve member 100 being carried by aflexible diaphragm 101 that cooperates with the housing means 11 todefine two chambers 102 and 103 on opposed sides thereof. The chamber102 is interconnected to the inlet 97 and is adapted to be fluidlyinterconnected to another chamber 104 formed in the housing means 11when the valve seat 99 is opened, the inlet 96 also being adapted to beinterconnected to the chamber 104 when the valve seat 98 is opened. Thepart 72 of the first passage means 66 is fluidly interconnected to apassage 105 formed in the housing means 11 and disposed in fluidcommunication with the chamber 103, the part 72 of the first passage 66intermediate the passage 105 and the valve 19 of the conditioncontroller means 17 also being interconnected to the chamber 102 by apassage means 106 that leads to the inlet 97. A restrictor 107 isdisposed in the part 72 of the first passage means 66 intermediate thepassage means 105 and 106 as illustrated in FIG. 2.

The inlet 96 of the switching device 95 is interconnected to the secondpassage means 89 by a branch passage means 108 that is disposedintermediate the normally opened pressure operated valve means 91 andthe valve of the controller means 18.

The chamber 104 of the switching device 95 is interconnected by apassage means 109 in the housing means 11 of the control device 10 to apilot pressure chamber 110 of a pneumatic relay portion 111 of thecontrol device 10.

As illustrated in FIG. 2, the pneumatic relay 111 has a pair of chambers112 and 113 formed in the housing means 11 and being separated by astationary valve seat 114 adapted to be opened and closed by a valvemember 115 normally urged to its closed position by a compression spring116 disposed in the chamber 112. The chamber 112 is adapted to beinterconnected to the inlet 14 of the control device 10 by a passagemeans 117 formed in the housing means 11 so as to always be in fluidcommunication with the source 13 whereby the chamber 112 is the mainpressure chamber of the relay 111. The chamber 113 is interconnected bya passage means 118 formed in the housing means 11 to the inlet 15 ofthe pneumatically operated heat exchanger device 16 whereby the chamber113 is a branch pressure chamber of the relay 111 and supplies thevarying pressure to the pneumatically operated device 16 to control thesame in relation to the pilot signal being received in the pilot chamber110 of the relay 1 11 by the controller means 17 or 18 in the mannerhereinafter described.

The inlet 15 of the pneumatically operated device 16 is alsointerconnected to the second passage means 89 by a passage means 119formed in the housing means 11 and having a restrictor 120 therein.

The pneumatic relay 111 has a movable valve seat member 121 carried bytwo flexible diaphragms 122 and 123 which are secured in the housingmeans 11 in such a manner that the same define a chamber 124therebetween which is interconnected to the atmosphere by a passagemeans 125 formed in the housing means 11 whereby the chamber 124 is anexhaust chamber for relay 111. The diaphragm 122 cooperates with thehousing means 11 to define the pilot pressure chamber 110 and thediaphragm 123 cooperates with the housing means 11 to define the branchpressure chamber 113.

The valve member 121 of the relay 111 has an opening 126 passingtherethrough and interconnecting the exhaust chamber 124 to the branchpressure chamber 113 at a valve seat 127 of the valve member 121.However, the valve member has an extension 128 adapted to pass throughthe stationary valve seat 114 and be engageable with the valve seat 127of the valve member 121 to close the valve seat 127 and thereby preventfluid communication between the branch pressure chamber 1 13 and theexhaust chamber 124.

The manual reset means of this invention for the control system 12 isgenerally indicated by the reference numeral 130 in FIG. 2 and comprisesa pneumatically operated valve means 131 having a pneumatic actuator 132for interconnecting a line or passage 133 to a port or passage 134 thatleads to the atmosphere when the pneumatically operated actuator 132 isdeactuated or when the actuator 132 is actuated and a manual lever 135is moved to a reset position thereof as will be apparent hereinafter.However, normally when the actuator 132 is pneumatically actuated byhaving its chamber fluidly interconnected by a line or passage means 136to the part 72 of the first passage 66 with the valve seat 70 in itsopen position, the valve means 131 is closed so that the conduit line133 is disconnected from the atmosphere line or port 134.

The passage 133 is interconnected by a passage 137 to the part 72 of thefirst passage means 66 as well as to the passage 105 of the switchingvalve 95, the passages 105 and 137 joining to the part 72 of the firstpassage means 66 intermediate the restriction 107 and anotherrestriction 138 disposed in the part 72 of the first passage 66intermediate the juncture of the passage 136 thereof and the juncture ofthe passages 137 and 105 thereto as fully illustrated in FIG. 2.

The restriction 138 in the part 72 of the first passage means 66 issized to be slightly larger than the restriction 107 therein so thateven with the night leak port 21 being wide open, the pressure in line72 between the restrictions 138 and 107 is substantially at the pressureof the source 13 and is adapted to feed through the passages 105 and 93to the cutoff valve 91 to shutoff the flow of any fluid through thepassage 89 to the day leak port nozzle 20 and reduces the airconsumption of the device 10.

As illustrated in FIGS. 6-9, the manual reset means 130 of thisinvention can be formed as part of the control device 10 by the housingor frame means 11 providing a tubular extension 139 adapted to receive aplunger 140 having an enlarged head 140A engageable with a flexiblediaphragm 141 carried by the frame means 11 and cooperating therewith todefine the pneumatic actuator 132 that comprises a recess 142 in asurface 143 of the frame means 11 that is closed by the flexiblediaphragm 141 to define a chamber 144 therebetween that is adapted to bein fluid communication with the passage means 136 previously described.

The lever 135 for the reset means 130 can have an end provided with anopening 151 passing therethrough and adapted to telescopically receivethe projection 140 while being rotatable on the end surface 152 of thetubular extension 139 of the frame means 11 about the axis of theprojection 140 as illustrated in FIGS. 8 and 9, the end 150 of the lever135 having two cone-shaped projections 153 extending therefrom towardthe actuator 132 with projections 153 being off center relative to thediameter of the part 150 of the lever 135 whereby such projections 153are disposed at approximately a 3:00 oclock position and a 7:00 o'clockposition when the lever 135 is in the full line position of FIG. 9. Atension spring 154 has one end 155 interconnected to the lever 135 andthe other end 156 thereof interconnected to part 157 of the frame means11 so that the force of the tension spring 154 normally tends to urgethe lever 135 in a rotational direction about the projection 140 of theactuator 132 against a stop means 158 of the frame 11 as illustrated byfull lines in FIG. 9 for a purpose hereinafter described.

Another lever 159 is provided for the reset means 130 of this inventionand has an end 160 also provided with an opening 161 passingtherethrough to telescopically receive the projection 140 as illustratedin FIG. 8 with the end 160 of the lever 159 being disposed intermediatethe head 140A of the projection 140 and the manually operated lever 135.The end 160 of the lever 159 also has two openings 162 passingtherethrough to respectively receive the cone-shaped projections 153 ofthe lever 135 when the lever 135 is in the full line position of FIGS. 8and 9.

The lever 159 has the other end 164 thereof provided with an opening 165for receiving a cylindrical projection 166 having an enlarged head 166Athat is engageable with the flexible diaphragm 141 adjacent anotherrecess 167 in the surface 143 of the frame means 11. The passage 133 isinterconnected to the recess 167 by a valve seat 168 of the frame means11 and the passage 134 to the atmosphere is also interconnected to therecess 167.

The lever 159 is adapted to pivot intermediate its ends 154 and 160against a knife edge fulcrum 169 of the frame 11 as illustrated in FIGS.6-9.

Since the lever 135 is normally held against the stop 158 by the tensionspring 154, such position of the lever 135 causes the opening 162 of thelever 159 to be in alignment with the cone-shaped pins 153 of the lever135 as illustrated by full lines in FIG. 9 whereby when the chamber 144of the actuator 132 receives pressure fluid by the pressure responsivevalve means 67 being opened to direct the source 13 into the part 72 ofthe first passage means 66, the flexible diaphragm 141 is moveddownwardly whereby an enlargement 170 on the projection 140 of thediaphragm 141 pushes against the end 160 of the lever 159 and causes thesame to pivot in a clockwise direction about the fulcrum line 169 asillustrated in FIG. 8 to hold the flexible diaphragm 141 in sealingengagement against the valve seat 168 of the passage 133 whereby thepassage 133 previously described is disconnected from the atmosphere.However, when the chamber 144 is disconnected from the pressure source13 in a manner hereinafter described, the chamber 144 returns toatmospheric condition so that the flexible diaphragm 141 no longer isimposing a downward force on the end 160 of the lever 159 whereby thevalve seat 168 of the passage 133 is opened to interconnect the passage133 to the atmosphere because of the passage 134.

However, during the previously described operation of the actuator 132wherein the same is pressurized by the source 13 to move the diaphragm141 against the valve seat 168 of the passage 133 as illustrated in FIG.8, if it is desired to operate the control system 12 with its daytimebleed nozzle 20 even through the higher pressure source is beingdirected by the source 13 into the system 12, the operator can grasp theend 171 of the lever 135 and move the same from the stop 158 inopposition to the force of the tension spring 154 against another stop172 as illustrated by phantom lines in FIG. 9 whereby such rotationalmovement of the lever 135 causes the cone projections 153 of the lever135 to cam out of the openings 162 ofthe lever 159 and act against theundersurface of the end 160 of the lever to pivot the lever 159 on itsfulcrum 169 as illustrated in FIG. 7 so as to interconnect the passage133 to the atmosphere for a purpose hereinafter described. With thelever 135 now moved to the phantom position illustrated in FIG. 9, thesame remains in such a position even though the operator releases theend 171 of the lever 135 because the force of the diaphragm 141 actingdownwardly at the actuator 132 against the end 160 of the lever 159presses the same in stacked relation against the pins 153 of the lever135 with sufficient force to maintain the same in the phantom positionof FIG. 9 by friction in opposition to the force of the tension spring154. However. when the pressure in the chamber 144 is released, thetension spring 154 overcomes the friction force against the pins 153 toreturn the lever 135 back to the full line position illustrated in FIG.9 where the pins 152 again are received in the openings 162 of the lever159.

From the above description of applicants improved pneumatic controlsystem 12 and the control device of this invention, it can be seen thatthe control device 10 is adapted to contain all of the system partsillustrated in FIG. 2 except for the pneumatically operated heatexchanger device 16 and the pneumatic source 13. However, it is to beunderstood that in order to practice the pneumatic control system ofthis invention, the various parts of the control device 10 could beseparately formed and interconnected by suitable conduits so that suchparts need not function in a unitary housing means as illustrated in thedrawings, as desired.

Accordingly, it can be seen that the control device 10 of this inventioncan be formed in a relatively simple and inexpensive manner to provideall of the components of the control system 12 of FIG. 2 except for thepneumatic source 13 and the pneumatically operated heat exchangingdevice 16 so that the control device 10 can be located on an inside wallof a building or the like completely remote from the pneumaticallyoperated heat exchanger means 16 to control the operation thereof in amanner hereinafter described, the control device 10 having the housing11 thereof made with ribs top and bottom to provide strength againstbending and warping with the leak port lever assemblies 25 and 26 beingmade in channel shape to provide stiffness together with heavy flexuresprings 29 and 30 to suspend such blade means 25 and 26 so that thecontrol device 10 is highly accurate and operates in a manner now to bedescribed.

Assuming that the lower pressure level of the pneumatic source 13, suchas 16 p.s.i., is to be utilized by the control system 12 for controllingthe pneumatically operated heat exchanger means 16 during the daytimeoperation wherein the condition controller means 18 will supply thepilot signal to the relay means 111 and that the higher the pressurelevel of the pneumatic source 13, such as 25 psi, will be utilized tooperate the heat exchanger means 16 during the nighttime operation ofthe system 12 wherein the condition controller means 17 will supply thepneumatic signal for the relay 111, and assuming that the operator hasset the cam member of the control device 10 in a desired set pointposition thereof wherein the previously calibrated adjusting means 39and 40 of the blade means 25 and 26 will provide a set point temperature of 70 that the heat exchanger means is to maintain during thedaytime and a temperature of during the nighttime, the operation of thecontrol system 12 during the daytime operation is as follows.

With the pneumatic pressure source 13 providing its lower outputpressure level, such as 16 psi, the spring 86 of the pressure responsivemeans 67 of the control device 10 maintains the diaphragm 73 against thevalve seat 70 so that no fluid pressure is supplied through the firstpassage means 66 of the control device 10 to the valve 19 of thecondition controller means 17. However, when such valve seat 71 of thepressure responsive means 67 is closed, no pressure fluid is beingsupplied to the actuator 92 of the normally opened valve means 91 sothat the valve means 91 is in its open position. Similarly, no pressurefluid is supplied to the chamber 103 of the switching device since theswitching device is maintained in its normally closed position under theurging of spring 95. Therefore, it can be seen that the low-pressurelevel of the source 13 is free to pass through the second passage means89 to the outlet 22 of the valve 20 of the condition controller means 18as well as through the branch passage 108 and into the chamber 104 ofthe switching means 95 since switching means 95 is maintained in itsnormally closed position under the urging of spring 95 holding valvemember against valve seat 99 preventing entrance of pressure fluid intocavity 102. With the valve member 1130 of the switching device 95closing the valve seat 99, it can be seen that the passage 89 of thecontrol device 10 is also interconnected intermediate the restrictor 94and the outlet 22 of the valve 20 of the condition controller means 18to the pilot chamber 110 of the relay 111.

with the bimetal member 24 of the condition controller means 18 sensingthe selected output temperature effect for the heat exchanger means 16,the bimetal member 24 is so positioned relative to the opening 22 of thevalve 20 of the condition controller means 18 that the pilot pressuresignal being delivered by the switching device 95, in the positionillustrated in FIG. 2, to the pilot chamber of the relay 111 is suchthat the relay 1 11 has the pressure in the branch chamber 113 thereofthat is supplied to the pneumatically operated heat exchanger means 16at a pressure level that maintains the heat exchanger means 16 at acertain position thereof that produces the output temperature effect atthe particular setting of the control device whereby not only is thevalve member 115 closed against the valve seat 114, but also the pilotpressure in the chamber 110 and the branch pressure in the chamber 113are so balanced that the valve member 121 has its valve seat 127 seatingagainst the extension 128 of the valve member 115 so that the branchchamber 113 is also out of fluid communication with the exhaust chamber124 whereby the system remains in the condition illustrated in FIG. 2.

However, should the output temperature effect of the heat exchangermeans 16 rise above the selected temperature setting of the cam 55 forthe daytime operation, the bimetal member 24 warps or moves closer tothe opening 22 of the valve 20 of the condition controller means 18whereby the pneumatic signal being delivered to the pilot chamber 110 bythe controller means 18 increases in pressure value so as to move thevalve member 121 downwardly and carry the valve member 115 therewith inopposition to the force of the compression spring 116 to open the valveseat 114 and, thereby, introduce an increased pressure in the branchpressure chamber 113. The increased pressure in the branch chamber 113is conveyed to the pneumatically operated heat exchanger 16 to cause thesame to decrease its output temperature effect proportional to theincrease in the pneumatic pilot signal being directed to the chamber 110by the controller means 18. When the decreased output of the heatexhanger means 16 brings the temperature adjacent the bimetal member 24back up to the selected temperature setting of the device 10, the relaymeans 111 returns to the position illustrated in FIG. 2. Conversely,should the output temperature effect of the heat exchanger means 16 assensed by the bimetal member 24 fall below the selected temperatureeffect, the decreased temperature being sensed by the bimetal member 24causes the same to warp away from the opening 22 of the valve 20 of thecontrol means 18 so that the pilot signal to the pilot chamber 110 ofthe relay 111 decreases in value. The resulting differential pressurebetween the pilot chamber 110 and the branch chamber 113 causes thevalve member 121 to move upwardly from the position illustrated in FIG.2 to open the valve seat 127 away from the valve extension 128 of thevalve member 115 so that the branch chamber 113 is interconnected to theatmosphere through the exhaust chamber 124. Accordingly, the pressure inthe branch chamber 113 decreases so that the pressure to thepneumatically operated heat exchanger 16 decreases whereby the heatexchanger means 18 increases its heating output proportionately to thedecrease in the pneumatic pilot signal being directed to the chamber 110at the relay 111 by the controller means 18. Thus, when the selectedtemperature effect setting of the control device 10 is subsequentlyreached by the heat exchanger means 16, the bimetal member 24 moves backtoward the valve member 20 of the controller means 18 to return therelay means 111 to the position illustrated in FIG. 2.

Therefore, it can be seen that the controller means 18, by varying theposition of the bimetal member 24 relative to the valve 20 thereof, isadapted to maintain a selected output temperature effect for the heatexchanger means 16 throughout the entire time that the pneumaticpressure source 13 is providing the control pressure at its lowerpressure level.

When it is desired to switch the system 12 over to its nighttimeoperation, either by manual change in the setting of the output pressurelevel of the source 13 or by an automatic timer switching operation, thechange in the output pressure level of the source 13 to the higherpressure level, such as 25 p.s.i., causes the system 12 to switch overto its nighttime operation so that the heat exchanger means 16 will becontrolled by the nighttime condition controller means 17.

In particular, when the pressure being directed into the part 71 of thepassage means 66 is at the higher pressure level of the source 13, suchincreased pressure in the chamber 76 of the pressure responsive means 67overcomes the force of the compression spring 86, which is set to beovercome by a pressure of about 20 p.s.i., when the two pressure levelsbeing considered are 16 psi. and 25 psi. as previously described,whereby the diaphragm 73 moves away from the valve seat 70 so as tointerconnect the pressure source 13 to the part 72 of the first passagemeans 66, and thus, to the valve 19 of the pressure control means 17.Simultaneously, the opening of the valve seat 70 directs fluid pressureto the actuator 132 of the reset means 130 and causes the normally openvalve seat 168 to be closed by the diaphragm so that the passage 133 isdisconnected from the atmosphere whereby the fluid pressure now beingcreated between the resistors 138 and 107 in the part 72 of the firstpassage means 66 is directed to the actuator 92 of the normally openedpneumatically operated valve means to cause the same to close andthereby disconnect the condition controller means 18 from the source 13.Also, since the pressure source must pass through the restrictor 107 inthe part 72 of the first passage means 66 before the same reaches thebranch passage 106 disposed intermediate the restrictor 107 and thevalve 19 of the condition controller means 17, a greater pressure isprovided by the branch passage 105 into the chamber 103 of the switchingmeans 95 than into the chamber 102 as provided by the branch passage 106so that the resulting pressure differential across the diaphragm 101causes the diaphragm 101 to move downwardly and overcome the force ofspring 95 and thereby move the valve member away from the valve seat 99and into engagement with the valve seat 98 to disconnect the chamber 104from the outlet 22 of the valve 20 of the condition controller means 18.

With the valve seat 99 now opened, it can be seen that the chamber 104of the switching device 95 is now interconnected to the valve 19 of thecontroller means 17 so that the pilot signal being directed by thepassage 109 into the pilot chamber 110 of the relay 111 is under theinfluence of the controller means 17 whereby the controller means 17operates the pneumatically operated heat exchanger means 16 in the samemanner as the controller means 18 previously described. Thus, suchoperation need not be further described except to state that thecondition controller means 17 operates the output temperature effect ofthe heat exchanger means 16 to tend to maintain the same at theparticular temperature setting level as has been previously selected bythe cam member 55 for nighttime operation.

The restrictor in the passage 119 that interconnects the pneumaticsource 13 to the branch pressure chamber 113 of the relay 111 isprovided to bleed the pneumatic pressure source 13 to the branchpressure chamber 113 to initially keep the relay 111 balanced with thevalve member 121 against the valve part 128 so as to prevent oreliminate a hysteresis effect.

Therefore, it can be seen that the improved control system 12 andcontrol device 10 of thisinvention are so constructed and arranged thatthe control device 10 is adapted to automatically switch the operationof the pneumatically operated device 16 between the controller means 17and 18 depending upon the change in pressure level of the pneumaticsource 13.

For example, with the control system 12 previously operating under thehigher pressure level of the pneumatic source 13, a subsequent change inthe output pressure level of the source 13 from its higher pressurelevel to its lower pressure level cause the flexible diaphragm 73 of thepressure responsive means 67 to close against valve seat 70 and therebyterminate the flow of fluid through the first passage means 66 to thecontroller means 17 whereby the previously closed valve seat 168 willopen to interconnect the atmosphere to the passage 133 and, thus, to thevalve 92 to open the same so that the source 13 is again interconnectedto the valve 20 of the condition controller means 13.

With the loss of pressure in the chamber 103 of the switching means 95by the closing of the diaphragm 73 against the valve seat 70 of thepressure responsive means 67 and the interconnecting of the passage 133to the atmosphere, the pressure in chamber 103 is exhausted allowingswitching means 95 to return to its normally closed position under theurging of spring 95' so that the system 12 is now completely switchedover to the lower pressure setting thereof whereby the controller means18 will operate the heat exchanger device 16 in the manner previouslydescribed.

The plunger means 83 of the pressure responsive means 87 of the system12 is so constructed and arranged that the end 85 thereof protrudes fromthe housing means 11 when the diaphragm 73 is moved upwardly because thepressure source 13 is providing its higher pressure control level.

This feature makes it possible to check the calibration of both leakport means of the controller means 17 and 18 of the control device or torecalibrate either in a building or the like with only the use of thehigher pressure output level of the source 13 because the operator canpush downwardly on the protruding portion 85 of the reset member 83 tomanually close the diaphragm 73 against the valve seat 70 so that at thehigher pressure level, the system 12 will be switched over from thecontroller means 17 to the controller means 18 for such checking orcalibration operation. This eliminates the need for the operator havingto switch the pressure level of the source 13 back to its lower pressurelevel to go through an entire building to check the calibration of thecontroller means 18 for each control device 10 after having gone throughthe same procedure with the controller means 17 at the higher pressurelevel setting of the pressure source 13.

While the above described use of the plunger 85 of the pressureresponsive means 67 can be utilized to temporarily switch over thecontrol system 12 to the daytime operation of the controller means 18when the source 13 is supplying the higher pressure level, it may bedesired to have the control system 12 operate with the daytimecontroller means 18 in a continuous manner even though the high-pressurelevel is being supplied by the source 13.

ln this latter situation, the manually operated reset means 130 of thisinvention can be utilized.

In particular, when the lever 135 of the reset means 130 is moved fromthe full line position of FIG. 9 to the phantom line position thereofwhen the system 12 is operating at the highpressure level thereof, theconduit or passage 133 is interconnected to the atmosphere and, thus,the chamber 103 of the switching means 95 and actuator 92 of the cutoffvalve 91 are interconnected to the atmosphere so that the compressionspring 95' moves the valve member 100 of the switching means 95 againstthe valve seat 99 and the cutoff valve 91 is opened so that the systemis switched over to the daytime pressure controller means 18 in themanner previously described and remains under the influence of thecontroller means 18 as long as the lever 13S remains in the phantom lineposition of FIG. 9. However, the lever 135 can be returned manually tothe position illustrated in full lines in FIG. 9 to return to nighttimeoperation by the controller means 17 if desired. However, when thecontrol pressure level from the source 13 drops to its lower pressurelevel, the diaphragm 73 of the pressure responsive means 67 closesagainst the valve seat 70 so that the controller nozzle 19 will bleedthe actuator 132 of the reset means 130 to its deactuated conditionwhereby the tension spring 154 can again return the lever 135 to therotational position illustrated in full lines in FIG. 9.

Accordingly, it can be seen that not only does this invention provide animproved pneumatic control system, but also this invention provides animproved control means and reset means for such a system or the like.

What is claimed is:

l. A pneumatic control system comprising a pair of condition controllermeans each having a sensor and a bleed-type pneumatic valve operatedthereby, a source of control fluid having two different control pressurelevels, a pneumatically operated device, relay means operativelyinterconnected to said source for directing a branch signal of saidcontrol fluid to said pneumatically operated device in relation to apilot signal directed to a pilot chamber of said relay means by saidcontroller means, first passage means for interconnecting said source tosaid valve of one of said controller means, second passage means forinterconnecting said source to said valve of the other of saidcontroller means, pressure responsive means in said first passage meansfor preventing fluid communication therethrough when said source is atone pressure level thereof and permitting fluid communicationtherethrough when said source is at its other pressure. level, thirdpassage means adapted to interconnect said first passage meansintermediate said pressure responsive means and said one controllermeans to said pilot chamber and adapted to interconnect said secondpassage means to said pilot chamber, switching means in said thirdpassage means having one position for interconnecting only said secondpassage means to said pilot chamber whereby the pilot signal for saidrelay means is provided only by said other controller means and havinganother position for interconnecting only said first passage means tosaid pilot chamber whereby the pilot signal for said relay means isprovided only by said one controller means, and reset means in saidfirst passage means intermediate said pressure responsive means and saidone controller means for switching said switching means from said otherposition thereof to said one position thereof when said source is at itssaid other pressure level.

2. A pneumatic control system as set forth in claim 1 wherein saidswitching means has means for automatically moving to said otherposition thereof to interconnect said first passage means to said pilotchamber of said relay means when said pressure responsive means providesfluid communication through said first passage means by said sourceproviding said other pressure level thereof and for moving to said oneposition thereof when said pressure responsive means prevents fluidcommunication through said first passage means by said source providingsaid one pressure level thereof.

3. A pneumatic control system as set forth in claim 2 wherein saidautomatic means of said switching means comprises pneumatically operatedvalve means.

4. A pneumatic control system as set forth in claim 3 wherein fourthpassage means interconnect said first passage means intermediate saidpressure responsive means and said one controller means to saidpneumatically operated means of said switching means and to saidpneumatically operated valve means;

5. A pneumatic control system as set forth in claim 4 wherein saidpneumatically operated valve means comprises a valve seat interconnectedto said fourth passage means, a pneumatic actuator, and movable levermeans operatively associated with a valve member means for opening andclosing said valve seat, said lever means being operativelyinterconnected to said actuator to be moved thereby.

6. A pneumatic control system as set forth in claim 4 wherein saidpneumatically operated valve means comprises a valve seat interconnectedto said fourth passage means, a pneumatic actuator, and movable levermeans operatively associated with a valve member means for opening andclosing said valve seat, said lever means being operativelyinterconnected to said actuator to be moved thereby.

7. A pneumatic control system as set forth in claim 3 wherein a fourthpassage means interconnects said first passage means intermediate saidpressure responsive means an said one controller means to saidpneumatically operated valve means.

8. A pneumatic control device comprising a housing means, a pair ofcondition controller means carried by said housing means and each havinga sensor and a bleed-type pneumatic valve operated thereby, said housingmeans having a relay means therein adapted to be interconnected to apneumatic source of control fluid having two different control pressurelevels for directing a branch signal of said control fluid to apneumatically operated device in relation to a pilot signal directed toa pilot chamber of said relay means by said controller means, firstpassage defining means in said housing means adapted to interconnectsaid source to said valve of one of said controller means, secondpassage defining means in said housing means adapted to interconnectsaid source to said valve of the other of said controller means,pressure responsive means in said first passage means of said housingmeans for preventing fluid communication therethrough when said sourceis at one pressure level thereof and permitting fluid communicationtherethrough when said source is at its other pressure level, thirdpassage defining means in said housing means adapted-to interconnectsaid first passage means intermediate said pressure responsive means andsaid one controller means to said pilot chamber and adapted tointerconnect said second passage means to said pilot chamber, switchingmeans in said third passage means of said housing means having oneposition for interconnecting only said second passage means to saidpilot chamber whereby the pilot signal for said relay means will beprovided only by said other controller means and having another positionfor interconnecting only said first passage means to said pilot chamberwhereby the pilot signal for said relay means will be provided only bysaid one controller means, and reset means in said first passage meansintermediate said pressure responsive means and said one controllermeans for switching said switching means from said other positionthereof to said one position thereof when said source is at its saidother pressure level.

9 A pneumatic control device as set forth in claim 8 wherein saidswitching means has means for automatically moving to said otherposition thereof to interconnect said first passage means to said pilotchamber of said relay means when said pressure responsive means providesfluid communication through said first passage means by said sourceproviding said other pressure level thereof and for moving to said oneposition thereof when said pressure responsive means prevents fluidcommunication through said first passage means by said source providingsaid one pressure level thereof.

10. A pneumatic control device as set forth in claim 9, wherein saidautomatic means of said switching means comprises pneumatically operatedmeans and wherein said reset means comprises pneumatically operatedvalve means.

11. A pneumatic control device as set forth in claim 10 wherein fourthpassage defining means is provided in said housing means andinterconnects said first passage means intermediate said pressureresponsive means and said one controller means to said pneumaticallyoperated means at said switching means and to said pneumaticallyoperated valve means.

12. A pneumatic control device as set forth in claim 10 wherein saidpneumatically operated valve means comprises a valve seat interconnectedto said fourth passage means, a pneumatic actuator, a movable levermeans operatively associated with a valve member means for opening andclosing said valve seat, said lever means being operativelyinterconnected to said actuator to be moved thereby.

13. A pneumatic control device as set forth in claim 8 wherein saidreset means comprises a pneumatically operated valve means which closeswhen said pressure responsive means permits fluid communication throughsaid first passage means, said reset means having manual means foropening said valve means when the same is closed by said pressureresponsive means.

14. A pneumatic control device as set forth in claim 13 wherein saidhousing means has a fourth passage means that interconnects said firstpassage means intermediate said pressure responsive means and said onecontroller means to said pneumatically operated valve means.

1. A pneumatic control system comprising a pair of condition controllermeans each having a sensor and a bleed-type pneumatic valve operatedthereby, a source of control fluid having two different control pressurelevels, a pneumatically operated device, relay means operativelyinterconnected to said source for directing a branch signal of saidcontrol fluid to said pneumatically operated device in relation to apilot signal directed to a pilot chamber of said relay means by saidcontroller means, first passage means for interconnecting said source tosaid valve of one of said controller means, second passage means forinterconnecting said source to said valve of the other of saidcontroller means, pressure responsive means in said first passage meansfor preventing fluid communication therethrough when said source is atone pressure level thereof and permitting fluid communicationtherethrough when said source is at its other pressure level, thirdpassage means adapted to interconnect said first passage meansintermediate said pressure responsive means and said one controllermeans to said pilot chamber and adapted to interconnect said secondpassage means to said pilot chamber, switching means in said thirdpassage means having one position for interconnecting only said secondpassage means to said pilot chamber whereby the pilot signal for saidrelay means is provided only by said other controller means and havinganother position for interconnecting only said first passage means tosaid pilot chamber whereby the pilot signal for said relay means isprovided only by said one controller means, and reset means in saidfirst passage means intermediate said pressure responsive means and saidone controller means for switching said switching means from said otherposition thereof to said one position thereof when said source is at itssaid other pressure level.
 2. A pneumatic control system as set forth inclaim 1 wherein said switching means has means for automatically movingto said other position thereof to interconnect said first passage meansto said pilot chamber of said relay means when said pressure responsivemeans provides fluid communication through said first passage means bysaid source providing said other pressure level thereof and for movingto said one position thereof when said pressure responsive meansprevents fluid communication through said first passage means by saidsource providing said one pressure level thereof.
 3. A pneumatic controlsystem as set forth in claim 2 wherein said automatic means of saidswitching means comprises pneumatically operated valve means.
 4. Apneumatic control system as set forth in claim 3 wherein fourth passagemeans interconnect said first passage means intermediate said pressureresponsive means and said one controller means to said pneumaticallyoperated means of said switching means and to said pneumaticallyoperated valve means.
 5. A pneumatic control system as set forth inclaim 4 wherein said pneumatically operated valve means comprises avalve seat interconnected to said fourth passage means, a pneumaticactuator, and movable lever means operatively associated with a valvemember means for opening and closing said valve seat, said lever meansbeing operatively interconnected to said actuator to be moved thereby.6. A pneumatic control system as set forth in claim 4 wherein saidpneumatically operated valve means comprises a valve seat interconnectedto said fourth passage means, a pneumatic actuator, and movable levermeans operatively associated with a valve member means for opening andclosing said valve seat, said lever means being operativelyinterconnected to said actuator to be moved thereby.
 7. A pneumaticcontrol system as set forth in claim 3 wherein a fourth passage meansinterconnects said first passage means intermediate said pressureresponsive means an said one controller means to said pneumaticallyoperated valve means.
 8. A pneumatic control device comprising a housingmeans, a pair of condition controller means carried by said housingmeans and each having a sensor and a bleed-type pneumatic valve operatedthereby, said housing means having a relay means therein adapted to beinterconnected to a pneumatic source of control fluid having twodifferent control pressure levels for directing a branch signal of saidcontrol fluid to a pneumatically operated device in relation to a pilotsignal directed to a pilot chamber of said relay means by saidcontroller means, first passage defining means in said housing meansadapted to interconnect said source to said valve of one of saidcontroller means, second passage defining means in said housing meansadapted to interconnect said source to said valve of the other of saidcontroller means, pressure responsive means in said first passage meansof said housing means for preventing fluid communication therethroughwhen said source is at one pressure level thereof and permitting fluidcommunication therethrough when said source is at its other pressurelevel, third passage defining means in said housing means adapted tointerconnect said first passage means intermediate said pressureresponsive means and said one controller means to said pilot chamber andadapted to interconnect said second passage means to said pilot chamber,switching means in said third passage means of said housing means havingone position for interconnecting only said second passage means to saidpilot chamber whereby the pilot signal for said relay means will beprovided only by said other controller means and having another positionfor interconnecting only said first passage means to said pilot chamberwhereby the pilot signal for said relay means will be provided only bysaid one controller means, and reset means in said first passage meansintermediate said pressure responsive means and said one controllermeans for switching said switching means from said other positionthereof to said one position thereof when said source is at its saidother pressure level. 9 A pneumatic control device as set forth in claim8 wherein said switching means has means for automatically moving tosaid other position thereof to interconnect said first passage means tosaid pilot chamber of said relay means when said pressure responsivemeans provides fluid communication through said first passage means bysaid source providing said other pressure level thereof and for movingto said one position thereof when said pressure responsive meansprevents fluid communication through said first passage means by saidsource providing said one pressure level thereof.
 10. A pneumaticcontrol device as set forth in claim 9, wherein said automatic means ofsaid switching means comprises pneumatically operated means and whereinsaid reset means comprises pneumatically operated valve means.
 11. Apneumatic control device as set forth in claim 10 wherein fourth passagedefining means is provided in said housing means and interconnects saidfirst passage means intermediate said pressure responsive means and saidone controller means to said pneumatically operated means at saidswitching means and to said pneumatically operated valve means.
 12. Apneumatic control device as set forth in claim 10 wherein saidpneumatically operated valve means comprises a valve seat interconnectedto said fourth passage means, a pneumatic actuator, a movable levermeans operatively associated with a valve member means for opening andclosing said valve seat, said lever means being operativelyinterconnected to said actuator to be moved thereby.
 13. A pneumaticcontrol device as set forth in claim 8 wherein said reset meanscomprises a pneumatically operated valve means which closes when saidpressure responsive means permits fluid communication through said firstpassage means, said reset means having manual means for opening saidvalve means when the same is closed by said pressure responsive means.14. A pneumatic control device as set forth in claim 13 wherein saidhousing means has a fourth passage means that interconnects said firstpassage means intermediate said pressure responsive means and said onecontroller means to said pnEumatically operated valve means.